ANAEROBIC-DIGESTION OF MUNICIPAL SOLID-WASTE - UTILITY OF PROCESS RESIDUES AS A SOIL AMENDMENT

Tuna processing wastes (sludges high in fat, oil, and grease [FOG]) an d municipal solid waste (MSW) generated on Tutuila Island, American Sa moa, represent an ongoing disposal challenge. The biological conversio n of the organic fraction of these wastes to useful products, includin g methane and fertilizer-grade residue, through anaerobic high-solids digestion is currently in scale-up development. The suitability of the anaerobic digestion residues as a soil amendment was evaluated throug h extensive chemical analysis and greenhouse studies using corn as an indicator crop. Additionally, native Samoan soil was used to evaluate the specific application rates for the compost. Experiments establishe d that anaerobic residues increase crop yields in direct proportion to increases in the application rate. Additionally, nutrient saturation was not demonstrated within the range of application rates evaluated f or the Samoan soil. Beyond nutrient supplementation, organic residue a mendment to Samoan soil imparts enhanced water- and nutrient-binding c apacities.